Lab 12 Flashcards
Natural selection describes
Differential survival and reproduction
As a result of natural selection what changes (evolutionary adaptation)
Populations change over generations and increase the frequency of traits suited to the environment
Selective advantage
A trait that increases fitness
Three general outcomes for natural selection on a population
Stabilizing selection
Directional selection
Disruptive selection
Stabilizing selection
Favors intermediate phenotype sand typically occurs in more stable environments where extreme phenotypes selected against
Directional selection
Shifts overall makeup of the population by selecting for one extreme
Common with environment changes
Disruptive selection
Balancing of two contrasting phenotypes
Occurs in patchy environments
Sexual selection
Specific form of natural selection in which individuals with certain traits are more likely than other individuals to obtain mates
Biological species concept
Group of populations whose members have potential to interbreed with one another in nature to produce fertile offspring
Prezygotic barriers vs. post zygotic
Block interbreeding before fertilization
Block interbreeding after fertilization
Temporal isolation
When mating occurs at different seasons or times of the day
Habitat isolation
When populations live in different habitats and do not meet
Behavioral isolation
When little it no sexual attraction exists between populations
Mechanical isolation
When structural differences prevent fertilization
Gametic isolation
Egg and sperm fail to unite
Reduced hybrid viability
Hybrid zygotes fail to develop to sexual maturity
Reduced hybrid fertility
When hybrids do not produce functional gametes
Hybrid breakdown
When hybrids of the next generation are feeble or sterile
Evolution
Genetic composition changes over generations
Evidence scientists have gathered to support theory
Homology (similarity in form or structure due to common ancestry) Fossil record ( ordered sequence of fossils) Biogeography (distribution of species in geographic space and evolutionary time ) Molecular biology (study of hereditary background of an organism that is documented in DNA)
